Switch-board for telephone-exchanges



(No Model.) 2 Sheets-Sheet 1.

P. BLAKE. SWITCH BOARD POR TELEPHONE EXCHANGES.

No. 392,403. Patented Nov. 6, 18.88

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(NOMQdel.) 2 sheets-sheet 2. y

F. BLAKE.

SWITCH BOARD FOR TELEPHONE EXCHANGES.' No. 392,403.` Patented Nov. 6, 1888.

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i UNITED STATES rPATENT Fries..

FRANCIS BLAKE, OF WESTON, MASSACHUSETTS.

SWITCH-BOARD FOR TELEPHONE-EXCHANGES.

` SPECIFICATION forming part of Letters Patent No. 392,403, dated No'vcmber 6, 1888.

Application filed August 10, 1888. Serial No. 282,431. (No model.)

To aZZ wh0m ama/y concern:

Be 1t vknown that I, FRANCIS BLAKE, of Weston, in the State of Massachusetts, have invented a new and useful Improvement in' Switch-Boards for Telephone-Exchanges, of which the following is a specication.

In themultiple switch-board now generally used in large telephone-exchanges there is apportioned to each operator a certain number of subscribers lines, normally grounded,each through a separate annunciator at the section of the board under the charge of such operator, but each branching to a spring-jack at the salue section.. When the drop of an annunciator falls, the ground of the line connected therewith is thereby cut outand the line remains connected with the spring-jack, there being a separate spring-jack as well as separate annunciator for each line belonging to that section. This same section of the board is also provided withan enormous number of other spring-jacks or plugholes, or similar terminals, a separate one in metallic connection with each separate subscribers line centering at the exchange, other than the lines first mentioned as grounded at the particular section-that is, each section of the board is provided with a spring-jack, or its equivalent,for and in metallic connection with each line normally grounded at such section, and with a separate spring-jack, or its equivalent, for and in metallic connection with each andeveryother line belonging to the exchange, and it follows that by a connecting-cord providedwith suitable plugs at either end the operator at each and every section can connect any line entering the exchange at his section with any other line belonging to the exchange.

The construction and operation of the multiple switchboard are attended with certain difliculties,whieh it is the object of my invention to remedy. Among other things, I wish to avoid the great cost attending its construction. In the multiple switch-board, as stated above, each line-wire entering the exchange must be provided with aseparate branch wire leading to each separate section of the board system. In practice it is found that each op- .erator can make the required connectionsin anspger to calls of about one hundredsubscribers, and 1t is found advantageous to have two lsubscribers7 lines normally grounded through annuneiators and connected with separate spring-jacks,or equivalents, at the two sections, andthe two sections together are provided with a separate spring-jack,or its equivalent, for every line entering the exchange, other than the two hundred. Thus in a board constructed for an exchange of iive thousand subscribers, each of the ve thousand subscribers7 wires has twenty-four branches leading to twenty-four double sections of the board, and thus there is required a multitude of branch wires and soldered connections. These I do away with. Again, since each line has so many branches with free ends at each of the several double sections, it is necessary that the operators at each double section shall be provided with apparatus. to test whether any required line to be called is already'in use `through any of its branches, and the testing apparatus in general use requires additional separate branch wires leading from each wire that enters the exchange to each double section of the board. The necessity for such testing apparatus is obviated by my invention. Again,when an exchange has outgrown the multiple switch-board originally provided or contemplated the original plant must be taken down, and practically an entirely new board built, for it is practically impossible to provide for a substantial increase without losing the benefit of the former construction, whereas a board originally constructed and operated according to my invention may be increased in capacity to any extent by mere addition to the original plant.

A further object of my invention is to lighten the labor of the operators in making connection between subscribers. How this is accomplished sufficiently appears in the description of the invention given below. It may be well to state here, however, that in practicing my invention the operators who lmake the connections do not answer the origi- IOO on telephonieconversation wiihthe calling subscriber. Further, it may be observed, although it will hereinafter` more fully appear, that in the switch-board constructed according to my system the lines of subscribers are grouped together notas calling-lilies butas lines to be called. In this rcspectmy system differs from any switch board system heretofore in use, and in this, as will hereinafter appear, lies its chief advantage.

The apparatus employed in practicing` my invention, besides liuc-wires and telephones, consists, essentially, in, first, a central or distributing board provided with terminals and grounded annunciators, one of each in each subscribers line; second, a number of connecting-tables through one or another of which each subscribers line passes to its said terminal and grounded annuneiators at the said distributing-board, there being in each of said lines a. springjack at that connecting-table through which the line thus passes, and, third, connecting-strips between said distributingboard and cach of said connecting-tables, each of said strips being provided with a connecting-cord or equivalent terminal at either end, and also with an annunciator at its respective connecting-table.

In the apparatus represented in the drawings both the annunciators of the main lines at thedistributing-table and those of the strips just mentioned at the connecting -table al'e grounded in branches of the line or strip, respectively, and the terminals of the main-lines at the distribnting-board as well as the terminals of the strips--i e, the connecting-cordsare open. A slight modification of this construction will hereinafter be referred to as a modification of my invention.

In the drawings, Figurel illustrates in diagram so much ofthe apparatus employed as it is necessary to exhibit for a full understanding of my invention. Fig. 2 illustrates indiagram the manner in which the Capacity of the system represented at Fig. 1 may be increased. Figs. 3 and fl show details of construction and modifications.

B is the distributing-board. As shown at Fig. 1, it is supposed to be of a capacity sufficicnt for one thousand subscribers, and is in two sections, one for subscribers7 lines numbered from 1 to 500, and the other for subscribers lines numbered from 501 to 1,001).

'Il and Ti are connecting-tables. Although but two are shown at Fig. 1 there will be in practice one connecting-table for every hundred subscribers7 lilies, and they will be known as table No. il, table No. 2, table No. 5,&e.

The subscribers lines entering the exchange are marked Ii with the number of the linethus Il, Ii52ft, &c. To avoid confusion, but few are shown. Iach subscribers line enters at its appropriate connecting-table, and, passing through a spring-jack, one for each line at that table, goes to the distributing-board, where it branches, one branch leading to a grounded annunciator and the other to an open terminal in the distributiiig-board. The springjacks at the connecting-table are marked J, with the number of the line J', .T52-l', &c. In like manner A, with the number of its line, designates an annunciator at the distributing-board. 1r, with the number of the line, represents that portion of the main line lying between the springjack at the connecting-table and the distributing-board.

G is a common ground for these annunciators. rIhe terminals in the distributing-board consist of themetallic linings of the plug-holes there shown, or they may consist of springjacks. rllhey have the numbers of their respective lines.

S" is a group or series of metallic strips or wires running from the distributing-board to the connecting-table No. O. S is a like group running to the eomiecting-table No. 5. In practice there is a separate group of these lnetallic S-strips between the distributing-board and each connecting-table, and it will be found in practice that iive of such strips in cach group will be ample in au exchange of one thousand subscribers, and it is believed that the larger the exchange shall be the fewer of such strips will be required between the distributing-table and each connecting-table.

.Each S-stri p terminates at the distributingboard in a connecting-cord, C, the -frce end of which, or the plug on the Afree cndof which, is adapted to be inserted in any of the plug-holes on the distrilmting-board. In like manner each S-strip has at its connecting-table a similar conneetingcord, c, whose plug is adapted to be inserted in any of the spring-jacks at that table. A branch from each strip terminates at its respective connecting-table in a grounded annnnciator-one for each strip. In practice the S connecting strips of each series are numbered 1 2 fl 4 5, and the corresponding annuneiators at each table are likewise numbered 1 2 3 Il rllhe common ground for the annunciators at each connecting-table is g. The respective operators at each section of the distributing-tablcand ateaeh connecting-table are furnished with the usual telephone apparatus of table-operators. (Not shown.)

The manner in which the invention is practiced will be understood from a description ol the condition of the apparatus shown at Fig. 1. Line 524 has called, the drop of annunciator 52.11 has fallen, and that annunci ator has lost its ground. The operator at section 2 of the distributing-table has plugged his telephone apparatus into terminal hole 521 of distributing-board and ascertained that line No.v il. is wanted. Disconnecting his teleph one apparatus he has plugged C-eord l (any unoccupied C-cord) into hole 5211-, and the drop of annunciator 1 at table No. Ollas fallen, and that annunciator has lost its ground. Then the operator at connecting-table No. Ollas connected connecting-cord c of strip s' with. iis own telephone apparatus, and in turn las asked the calling subscriber' what connection lOO iro

is wanted, and the calling subscriber has again replied that linel is Wanted. Finally the operator at the connecting-table has plugged connecting-cord c into spring-jack J, and the dcsired connection between line 524. and line 1 is accomplished. Theplug on the end of conneeting-cord c has one insulating face and has cut out W A and terminal 1 at distributingboard. y

The C-cord used as above might normally be connected with plug-hole 524 and form the open terminal of line 524 and in the operation be plugged into the strip Without departing from my invention. In fact,although the construction would cost more,the work of the operator at the distributing-table would be alittle more expeditious if all the cords were normally attached to the distributing-board,siuce he would use the same cord to connect his telephone with the calling-line that he uses to connect the calling-line with the stripjust as the operator at the connecting-table uses the same cord to connect his telephone with the calling-line that he uses to connect the callingline with the desired line. In either case these cords are weighted 'and drawn behind their strips or board,as the case may be, so that their plugs or ends with which a connection is to be made are within ready reach of the operator. (See Fig. 3.) It is evident also that Without departing from myinvention theannunciators, whether at the distributing-table. or at a connecting-table, might be grounded through the terminal, the latter being slightly modified in construction, or the spring-jack form being nsed,and remain in circuit whenever the lines are connected. Such a construction is shown at Fig. 4, Where the terminal is in` the form of a spring-jack, jm. One face of the connectingplug on cord C is here of insulating material, and when inserted in the spring-jack cuts off the ground g and leaves the annunciator in the working line. A modiiication of like nature will leave the annunciators at the connecting-tablein the line.

It is thought that an operator at the distributing-board will have suflicient work in attending to five hund red lines,and that an opcrater at a connecting-table will have sufficient work in attending to one hundred lines; but the capacity of the switch-board may be increased to any extent by making a new section of distributing-board for every additional five hundred subscribers7 lines, providing a new connecting-table for each additional one hundred subscribers, and furnishing a set of connecting-strips between each section of the distributing-board and each connecting-table. It has been stated above, however, that a set of live strips leading to each table is suiiicient for a distributing-board having provision for one thousand subscribers lines. Therefore but a single set of strips is needed between each connecting-table and two adjoining sections of the distributing-board of the capacity of tive hnndred lines each, as shown in Figs. 1 and 2.

Fig. 2 shows the switch-board'of Fig. 1 increased to a capacity of two thousand subscribcrs. Further description of Fig. 2 is unnecessary, unless, perhaps, it may be well to say that the general system of lettering and numbering used in Fig. 1 has been followed in Fig. 2.

I claim- In a switch-board for a telephone-exchange, the combination, with the linewires, of, first, the distributing-board provided with terminals and grounded annunciators, one of each for each line-wire; second, connecting-tables through which the said line-wires or subscribers7 lines pass in groups to their respective said terminals and annuneiators at the said distributingboard, there being in each of said lines a spring-jack at that connecting-table through which the line thus passes, and, third, connecting-strips between said distributing-board and each of said connecting-tables, each of said strips being provided with a connecting-cord or similar terminal at each end, and also with an annunciator at its respective connectingtable, substantially as described.

' FRANCIS BLAKE.

Witnesses:

W. W. SWAN, WM. S. RoGnRs. 

